Meristematic tissue is a plant tissue that is undifferentiated and can divide to form other tissues. It is found in three main regions: the apical meristem at the tips of stems and roots, the intercalary meristem at the bases of leaves and stems, and the lateral meristem or cambium responsible for increasing the girth of stems and roots. Permanent tissues are differentiated tissues that do not divide, such as parenchyma, collenchyma and sclerenchyma. Epithelial tissue forms protective layers in animals, such as the skin and lining of organs, while connective tissue binds and supports other tissues.